Case Studies

Removing a One-Piece Bridge in Tacoma

INDUSTRY

Construction

EQUIPMENT USED

Liebherr LR1600 Crane with 217’ boom and approximately 1.25 million lbs. of counterweight

Public transportation requires constant upkeep. That means building new bridges, tracks, and roads but also removing old materials to make way for the new. The process is complex. Fortunately, Omega Morgan’s crane services team specializes in complex processes that involve heavy lifting.

For this job, our Seattle office worked with Atkinson, a Tacoma, Wa. construction company charged with replacing an aging bridge. Before the process could begin, the old bridge had to come off. That’s where our team came in.

The Problem: A One-Piece Move in a Challenging Location

Taking out the old bridge was not as simple as taking it apart. It needed to be lifted in one piece, in order to minimize the impact and potential damage to the railways beneath. A simple crane wouldn’t do; we needed a specialized crane to get the work done.

In addition, the rigging needed to be just right. We estimated the bridge weight to be about 600,000 pounds. To avoid potential falling or other complications, we had to make sure that the crane and rigging was as secure as it was strong. Not an easy proposition, and one that called for an experienced team.

The Process: Custom Design, Plan, and Preparation

The challenges presented by this project were complex. But we are used to custom needs, so our process was pretty straightforward. First, we brought in an LR 1600, a crane large enough to both lift and carry the bridge. Its 217′ boom and ability to balance 1.25 million pounds of counterweight was perfect for the job.

Once the crane was set up, work on the rigging began. That required custom softeners, built specifically for the equation, as well as 6-part braided slings with a three-quarter inch component diameter. These slings, combined with the softener, worked perfectly in keeping the D/d ratio from compromising the strength of the basket sling connections between the crane and bridge.

Prior to lifting the bridge, we also had to confirm its weight in order to make sure the rigging was just right. Jacking up the bridge to confirm its weight and center of gravity showed that the actual weight, 599,000 pounds, was extremely close to our original estimate of 600,000 pounds.

With that confirmation in hand, the actual movement and transportation went without a hitch. Omega Morgan lifted the bridge, then set it on the approach for demolition. As expected, the entire process was accomplished in one piece and one lift.

The Result: Moving a Public Transportation Process Forward

When bridges become unsafe, they eventually need replacing. As anyone familiar with the process knows, this is a massive job for construction companies who specialize in building, not removal. That only gets complicated when the bridge in question has to be removed in one piece.

Fortunately, Omega Morgan was up for the job. Our expertise in crane rigging and heavy pieces of machinery and equipment came in handy as we prepared, moved, and placed the bridge exactly as required. The result was another satisfied customer, able to do their job in building the new bridge, thanks to easy removal of the aging model.